REGULATORY DIFFERENCES IN DEVELOPMENTAL EXPRESSION OF ALCOHOL-DEHYDROGENASE ARE RELATED TO INTERSPECIES DIFFERENCES IN ETHANOL TOLERANCE OFDROSOPHILA

Biochemical properties and expression patterns of alcohol dehydrogenas e were compared among members of the virilis phylad of Drosophila. Qua ntitative differences in stage- and tissue-specific expression of ADH of D. vivilis, D. novamexicana, D. texana and D. americana were observ ed. These differences seem to correlate with the temporal differences in ethanol tolerance among these species. Quantitative differences in ADH protein levels account for most, if not all, of the activity diffe rences between species. Analysis of the interspecific hybrids revealed that these differences arise by a mechanism affecting monomer synthes is. A comparison with earlier studies, where independently evolved reg ulatory differences were related to adaptations, revealed contrasting underlying mechanisms.